This invention relates to heat seal apparatus, and more particularly to such apparatus which includes a manually operable heated roller which may be pressed on a package or the like enwrapped with a suitable synthetic resin heat seal film or the like for heat sealing the film to itself or to the package.
In many heat seal applications, such as in wrapping packages on a packaging line, it is desirable to wrap the package in a covering of plastic film for protecting and sealing the package. As is well known, this plastic film is typically heat sealable to itself (or to the package) for securing the film in place on the package.
Heretofore, in relatively low volume operations (i.e., on non-automated packaging lines) it was conventional to use a portable heated roller having an insulated handle thereon which the user may roll across the film enwrapped around the package for heat sealing purposes. Such a portable heat sealing roller is shown in U.S. Pat. No. 3,857,015. However, while this prior art heat sealing roller worked well for its intended purposes, it will be appreciated that the necessity of locating an electric resistance heater within the roller presented substantial design difficulties. For example, since the roller rotated relative to the handle or frame of the heat sealing implement, it was necessary to provide some type of a rotary electrical connection for the heater. Also, it was necessary that the electric resistance heater be in heat transfer relation with the entire outer surfaces of the roller. Still further, it was necessary that the roller be connected to a source of electrical supply by a power cord which interfered with use of the roller.
Also known were heavy metal rollers rotatably mounted in a frame having a thermally insulated handle thereon wherein the solid metal roller of copper, aluminum, or other relatively highly heat conductive metal with a relatively high heat capacity, would be heated to a predetermined temperature level. Then, the user, free of an electrical cord, could readily apply the roller to a heat sealable film to be heat sealed. However, the necessity of utilizing a solid metal roller meant that these rollers were, in some instances, excessively heavy for ready manual use. If hollow metal rollers were used in an effort to lessen the weight of the roller, the roller would not have sufficient heat capacity to heat seal relatively large areas of heat sealable film without having to be reheated.
Thus, there has been a long-standing need for a lightweight, cordless manual heat seal roller which had sufficient heat capacity to heat seal relatively large areas of heat sealable film.